It wasn’t on the White House’s official schedule, but on Nov. 22, Sen. Chuck Schumer (D-N.Y.) quietly slipped into the Oval Office on a self-appointed mission to steel Barack Obama for the tax cut fight.

Schumer, the newly anointed message guru for besieged Senate Democrats, told Obama he wanted the president to hold the line and oppose Republican efforts to extend the cuts to families making more than $250,000.

But Obama, according to people briefed on the hourlong one-on-one meeting, was cool and noncommittal, especially when Schumer pitched his pet plan to extend the cuts to families making up to $1 million per year — a move designed to corner Republicans into defending millionaires and billionaires.

Schumer was irked, according to people he’s spoken to subsequently, deeply disappointed and convinced Obama had missed a major opportunity. The White House, in turn, was incensed when it learned Schumer planned to push forward with votes — ultimately unsuccessful — on alternative Democratic proposals.

“The bottom line is that he had a short-term partisan strategy for point scoring that would have been really costly in the long run and for which people would be properly angry,” said a top administration official. “He's a smart guy. This wasn't a smart or practical strategy.”

Since then, the relationship between Schumer and Obama, arguably the Democratic Party’s two most influential message strategists, has become so strained both sides are working to patch things up for fear their differences could hinder Democrats in the face of a strengthened and determined GOP opposition.

Publicly, Obama and his staff have played nice with Schumer and predicted that Democratic opposition to the controversial bipartisan tax cut deal will soon dissipate when leaders realize the president negotiated the best possible deal given his weak hand.

“My sense is there are going to be discussions between both House and Senate leadership about all the final elements of the package,” Obama told NPR on Thursday. "Here's what I'm confident about: that nobody — Democrat or Republican — wants to see people's paychecks smaller on Jan. 1 because Congress didn't act."

But privately, White House officials, who have long viewed Schumer as a talented but essentially self-promotional operator with no abiding loyalty to Obama, think he was pursuing an irresponsible partisan fight that would delay the tax cuts and the extension of unemployment benefits for months. And Obama himself warned Schumer that the millionaire strategy could sink the stock market.

When a vote on the millionaire plan came up short last Saturday, the administration gloated — and mocked Schumer for overestimating his support in meetings with West Wing officials.

"Sen. Schumer says he wants a fight? He couldn't hold his caucus together," an anonymous White House official told ABC’s Jake Tapper earlier this week.

White House press secretary Robert Gibbs said as much on Nov. 30, when a reporter asked whether Schumer’s proposal could be the basis for a bipartisan compromise. “I don’t, quite frankly ... I don’t see that it has moved any Republican[s],” Gibbs said.

A person close to Schumer said he was “surprised” and found it “unprofessional” that the White House was “taking shots” at him.

But the Obama-Schumer flare-up is rooted less in details of the tax cut debate than in a deeper conflict over the future course of the Democratic Party in the wake of its shattering losses in the November midterms.

If Obama wants to elevate beyond Washington’s partisan fray to win back independents in 2012, Schumer’s goal is to defeat the GOP opposition and secure a sustainable Democratic majority, using targeted policy positions.

And Schumer now has the platform to do that, since Reid, who was nearly ousted by tea party challenger Sharron Angle, has ceded much of his rapid-response and messaging duties to him.

The elevation of Schumer, who oversaw historic Democratic pickups in the 2006 and 2008 cycles as chairman of the Democratic Senatorial Campaign Committee, poses a new challenge to Obama, who had enjoyed dominance of the party’s national messaging operation over the past two years.

The millionaire tax cut proposal, which had some support in Obama’s own Treasury Department, was especially infuriating to Obama’s staff, who viewed it as a serious threat to the bipartisan deal the president, aided by Vice President Joe Biden, was working out with Senate Minority Leader Mitch McConnell (R-Ky.).

“The White House is fuming [over Schumer] because they are being forced to deal with a much more antagonistic leader [than Reid],” said a Senate aide who knows both men.

Added one person in Obama’s orbit: “The White House has been used to getting their way, and Chuck represents a real change for them. ... He’s relentless, he’s self-promotional and he’s not loyal. But he’s just what [the Senate] needs.”

Although Obama and Schumer have never been close, they have maintained a distant, somewhat grudging mutual respect. Schumer, a stocky, garrulous, impatient son of a Brooklyn exterminator, is the stylistic opposite of a president who prides himself on cool.

Their paths have crossed often over the past six years, but they never seemed to click.

During the 2006 cycle, then-Sen. Obama was the Democrat most sought after for fundraising and rallies, and Schumer, in his role as DSCC chairman, worked with his staff to set up a crowded schedule of appearances. But Obama largely decided his own itinerary, often geared to his own political priorities, and viewed his interactions with Schumer as something of a chore.

During one meeting with Schumer and several other senators that year, Obama expressed annoyance at small talk and urged the stunned New Yorker to “move things along more quickly,” according to one witness, who described Schumer as “somewhat taken aback.”

But Schumer has always recognized Obama’s talent and made sure to keep his private channels open to him during the 2008 presidential primary despite his support for New York’s then-junior senator, Hillary Clinton.

Schumer’s differences with Obama began to surface in mid-2009, when he counseled the president to ditch his effort to pass a comprehensive health reform bill, arguing that the White House needed to be more focused on the faltering recovery and rising unemployment rate.

Obama's former chief of staff Rahm Emanuel, who served as head of the Democratic Congressional Campaign Committee when Schumer ran the DSCC, was a buffer between the two men. But Emanuel’s departure to run for mayor of Chicago has forced Schumer to do business directly with Obama or interim chief of staff Pete Rouse, whose low-key style doesn’t mesh nearly as well with the high-octane senator, sources say.

Whatever his private feelings about Obama, Schumer has stayed positive in public, keeping the door open to reconciliation. When asked what advice he’d give the president during a Nov. 14 appearance on CBS, Schumer replied:

"My advice is very simple. It would be the same to the president, to my colleagues in the Senate and House, to people of the other party: Focus on the middle class like a laser," Schumer said.

And earlier this week, during a closed Democratic Caucus meeting, Schumer brushed back several senators outraged by Obama’s claim that opponents of his tax deal were “sanctimonious” — saying, “I don’t think the president was speaking about us.”